2013/9/27 ko1 (Koichi Sasada) <redmine / ruby-lang.org>:
> Issue #8953 has been updated by ko1 (Koichi Sasada).

> And all of versions ignore the redefinition.
> I implemented 1.9 VM as this behaviour because I think it is spec.

I also think so.
The spec is one of the reason Ruby can assign named capture to local variable.

% ruby -e '/def(?<var>.*)/ =~ "abcdefghi"; p var'
"ghi"
-- 
Tanaka Akira